In general, proportional integral (PI) control, proportional integral differential (PID) control, robust control, and the like have been known as control schemes for stabilizing a control amount of a control target.
A conventional feedback loop such as an analog PID control encounter limitations in transient response characteristics. Thus, an analog circuit may employ a method in which a current flowing in a coil is feedback controlled. This control method is called a current mode.
For example, an optical device may adjust a position of a correcting lens by using the PID control.
However, the optical device encounters a problem in that when disturbance occurs in the correcting lens as a control target, it takes a long period of time for the correcting lens to be stabilized.
When realizing the control method in the case of using a digital power source, an analog-to-digital (AD) converter for monitoring a current is required in addition to a voltage loop, thereby increasing external installation components such as a coil, a resistor, and the like, or the number of pins, and also increasing a circuit area and power consumption.